The importance of source behavior in distinguishing populations of epileptic foci

The interictal spike discharge is usually analyzed in terms of amplitude, morphology, location of spike negativity, frequency or pattern of occurrence, and the effect of sleep/wake cycle. Such information derived from the routine EEG supports the clinician in the diagnosis, treatment, and management of the epileptic patient. Detailed analytical or computerized studies of spike characteristics have not had a great deal of clinical impact to date. This communication presents an argument for characterizing the epileptic focus based on interictal spikes. Some findings from quantitative analysis of spike properties are reviewed. By facilitating the creation and refinement of hypotheses relating to the underlying neuronal mechanisms, mathematical source modeling (or dipole modeling) may enhance our understanding of the epileptic process. Such an approach is applied to rolandic epilepsy as an example, and a model is proposed that is parsimonious with experimental data and clinical observations.